Electronically commutated motors or ECMs provide variable speed operation while maintaining an efficiency of 70% over the speed range thereby affording a major reduction in power consumption as compared to conventional motors. The speed of an ECM can be detected to provide speed indicating information to an electronic commutating circuit which commutates the ECM in response thereto. The control signal for commutating the ECM is indicative of a desired condition to be achieved and controls the degree of energization of the stator windings of the ECM. The use of ECMs for circulating air delivery in a furnace, for example, incorporates an adaptive blower motor control algorithm which involves adjustment of the blower motor speed input signal to provide the desired air delivery. Conventionally, each motor is adjusted by selecting the appropriate speed tap to obtain the desired air delivery. In addition to the time and labor involved in individual calibration, the resultant calibrations are subject to the effects of aging, temperature drift and variations in load.